This document discusses different types of natural disasters including floods, earthquakes, cyclones, and provides information on disaster management. It defines a disaster as a sudden event that disrupts a community's normal functioning. Disaster management aims to prevent disasters, minimize effects, and help recovery. The disaster cycle has risk reduction and recovery phases. Floods occur when water levels in streams exceed bank heights due to heavy rain. Earthquakes are caused by the movement of tectonic plates. Cyclones have spiraling winds that can cause heavy rain and flooding. Disaster management strategies seek to minimize risks through preparedness, mitigate impacts during events, and aid rehabilitation after.

1. DISASTER MANAGEMENT
Disaster: -
A disaster is a sudden accident or natural catastrophe that seriously disrupts the functioning of a
community or society causing a great damage or loss of life.
The losses exceed the community or society’s ability to cope up using its own resource
Disasters are of two types
Manmade/Artificial Disaster: Human activities are responsible for loss of life and effect on
environment. Example- Industrial explosions, Nuclear Accidents.
Natural Disasters:
Geophysical- Earth quakes, Volcanic Eruptions
Hydrological- Floods
Climatological- Forest fires, Droughts
Materiological- Cyclones, Storms
Biological- Disease epidemic (Abola)
DISASTER MANAGEMENT
Dealing with the organization and management of resources and responsibilities towards all
humanitarian aspects of emergencies to lessen the impact of disasters
It involves
 Preventing the calamities
 Minimizing the effects
 Taking timely returns for normalizing the situation
Disaster management is a chain of activities carried out before, during and after disaster occur
DISASTER CYCLE
Disaster cycle divided into 2phases
Phase I: Risk reduction phase /Pre-disaster Management phase
Phase II:Recovery Phase / Post -Disaster Management phase
Risk reduction before disasters
 Mitigation and preparedness - town planning
Fore casting
Choose shelter
Mock drills & Awareness programs
Recovery phase after disasters
 Response

2.  Rehabilitation
 Reconstruction
Response
- Involves searching the rescue and giving first aid.
- Field care.
- triage (process of rapidly classifying the injured on the basis of the severity of their
injuries and livelihood of their survival).
Injury Colour code priority
Immediate red 1
delayed yellow 2
minimal green 3
expectant Black 4
- death management
- vaccination
-
 Rehabilitation:
- Water supply
- Food safety
- Sanitation and personal hygiene
 Reconstruction
- Communication services
- Transport
- Rebuilding of affected areas (hospitals, institutions).
Floods
The Excess flow of water in a stream covering the adjacent land due to increased rainfall or melting
the snow that disrupts the functioning of the community/society by causing a great damage or loss of
life is called flood.
“Excess flow of water in a stream covering a adjacent land is called a flood”
Most of the rivers or stream have water level well below the bank height throughout the year. But due
to heavy rain fall the level of flow increases. This covers the nearby land and causes a great loss or
damage.
Flood plain/level: -
 Defined in terms of a flood frequency
 Flood frequency usually referred as 10-year flood,100-year flood etc.
 Flood plains generally fertile, flat and easily formed.
 Most part of the world, flood plains are usually developed with buildings and towns and
cleared of vegetation.
A 10-year flood at any point in a stream is that discharge of water which may be expected to occur on
average once in 10 years.

3. Flood way: -
 Lowest part of the flood plain is termed as flood way.
 It is the reserved portion for the passage of the flood.
 No development is allowed in this portion.
Flood fringe: -
 The land portion available on both side of a stream are called flood fringe.
 Developmental activities allowed in this portion
Severity of floods can be depending on the frequency of flood and depth of water that flows in a
stream. Loss due to flood is usually costlier than the other natural disasters because they occur
relatively frequently and in populated river corridors.
Causes of flood:
Most of the human activities lead to the frequency and severity of flood. some of them are
 Heavy rain fall
 Construction of buildings and dams
 Removing vegetation
 Paving roads and parking areas
 Deforestation
 Urbanization
 Mining
 Earth quakes
 Cleared off vegetation/Agricultural lands
Effects of floods: -
 Erosion of topsoil and vegetation
 Damage and loos to land, houses and properties
 Spreading of endemic water borne diseases
 Interruption of basic facilities of community such as highways, railways, telephone,
electricity and day to day essentials.
 Silting of reservoirs and dams
Control measures of flood: -
 Construction of flood control dam
 Deepening, widening and straightening of streams
 Lining of streams
 Banning construction of buildings in flood plain
 Reduction of mining (minimal usage)
 Converting flood plains into wildlife habitation, parks and recreation areas
 Afforestation
Management of flood: -
Before during after
Town planning Off electricity Clean and disinfect water
supply
Dams (flood planning) Protect vulnerable
Weather Fore casting contamination

4. EARTH QUAKES:
An earth quake occurs when rock break and slip along a fault in the earth
Energy is released during an earthquake in severalforms, includes
- a movement along the fault,
- as heat,
- as seismic waves and causes ground to shake, sometimes hundreds of kilometers away
Causes of earthquakes: -
 Occur from the deformation of the crust and upper mantle of the earth.
 Middle portion of the earth is in molten stage.
 Due to heating and cooling of the rock below these plates, causes movement of adjacently
overlapping/ sliding of plates under the great stress,deformation occur.
 Displacement of the plates is about 2 -12 cm/yr.
Sometimes tremendous energy can build within a single or between neighboring plates. If the
stress exceeds the strength of the rock. Rock breaks suddenly, releasing the stored energy as an
earth quake. The earth quake release energy in the form of waves which are radiating from
epicenter in all directions. The different types of energy waves shake the ground in different ways
and also travel through the earth of different velocities.
P waves (Primary) S waves (Secondary)
Primary and fastest wave Slower than p waves
Shakes the ground in same direction it is
travelling
Shakes the ground up and down, perpendicular
to the direction of movement
Same direction of movement Perpendicular direction of movement
Can move through solid and fluids like
water/liquid layers of the earth
Can only move through solid rock
Magnitude of earthquake:
The magnitude of earth quake is usually measured in Richter scale.
Logarithmic, that an increase in one magnitude unit represents a factor of ten times in amplitude.
E.g.; - 6 magnitude unit of earth quake 5 magnitude unit of earth quake
6 M > 5M
10 TIMES IN AMPLITUDE
Intensity of earthquake varies greatly according to distance from the earth quake ground conditions
and other factors. Depending on magnitude earthquakes are classified in categories ranging from
minor to great.
Class Magnitude
Great 8 or more
Major 7 – 7.9
Strong 6 - 6.9
Moderate 5 – 5.9

5. Height 4 – 4.9
Minor 3 – 3.9
Effects of earthquakes:
1) Ground shaking: - the vibration of ground during an earthquake, caused by body and surface
seismic waves.
Building can be damaged
2) Liquefication of ground: - when water and soil are mixed the ground becomes very fast
becomes very soft and acts similar to quick sand. If liquefication occur under a building, it
may start to lean, tip over or sink severalfeet.
3) Ground displacement: - if a structure (a building, roods etc.) is built across a fault the ground
displacement during an earthquake could seriously damage or rip apart that structure.
4) Landslides: - sliding of rocks and soil on both sides of a hilly area.
5) Flood: - an earth quake can damage the dams which would then flood the area damaging
buildings and may be sweeping away or drowning people.
6) Fire: - caused by broken gas line and power lines or tipped over wood or coal stones.
7) Tsunami: - there are water waves that are caused by sudden vertical movement of a large area
of the sea during an under-sea earthquake. More destruction near sea shores.
Control measures of earth quake
 Safes places indoors/outdoors must be clearly identified (away from trees,bridges, power
lines).
 Emergency communication plan should be made available.
 Alt the building in seismic zones need to be designed so that they withstand major tremors.
 Disaster management supplies (like flash lights, first aid box etc.) should be available in
hand.
 Should stay away from tall and heavy objects.
CYCLONES:
Spiral movement of wind towards a low pressure center is called a cyclone.
Storms associated with low pressure and rising air are known as cyclonic storms.
Northern hemisphere: - wind in a cyclone is anti-clock wise.
Southern hemisphere: - wind movement is clock wise
Cyclones with wind speed of exceeding 73 miles/hours called hurricanes.
Wind with less than 39 miles/hours of wind speed is tropical depression.
Winds with 39 – 73 miles/ hours called tropical storms.
Causes:-
 Atmospheric instability.
 Sufficiently warm sea surface temperatures
 High humidity in the lower to middle levels of troposphere
 Low vertical wind shear
Effects of CYCLONES:-

6.  Heavy rainfall and flooding
 Storm surges (abnormal size in water occur during a cyclone)
 Damage in coastalareas/regions
 Altering of land scape and remove forest canopy
 Strong winds (destruction of smaller buildings, knock out power etc.)
Control measures:-
 Meteorological information should be informed to the people as early as possible.
 Minimization of developmental activities along the frequently affected areas.
 Adopting modifications in construction techniques to the building in frequently affected
areas.